Question: $ C = \left[\begin{array}{rrr}2 & 1 & 2 \\ 0 & 0 & 1 \\ 2 & 2 & 1\end{array}\right]$ What is $ C^{-1}$ ?
Solution: $ = \left[\begin{array}{rrr}1 & -\frac{3}{2} & -\frac{1}{2} \\ -1 & 1 & 1 \\ 0 & 1 & 0\end{array}\right]$